Method for the asymmetric dihydroxylation of olefins, using osmium catalysts

ABSTRACT

This invention relates to process for asymmetric dihydroxylation of olefins using osmium catalysts to obtain monofunctional, bifunctional, and/or polyfunctional chiral 1,2-diols of the formula (I) 
     
       
         R 1 R 2 C(OH)—C(OH)R 3 R 4   (I) 
       
     
     where R 1  to R 4  are defined herein, by reacting an olefin of the formula (II) 
     
       
         R 1 R 2 C═CR 3 R 4   (II) 
       
     
     where R 1  to R 4  are defined as for formula (I), 
     with molecular oxygen in the presence of an osmium compound and a chiral amine ligand in water or a water-containing solvent mixture at a pH of from 8.5 to 13.

The present invention relates to a process for preparing chiral1,2-diols from olefins using catalysts based on osmium compounds. Chiral1,2-diols are of industrial importance as fine chemicals and asintermediates for pharmaceuticals and for active compounds in theagrochemicals sector.

The standard method of synthesizing chiral 1,2-diols is the Sharplessdihydroxylation reaction in which olefins are reacted in the presence ofosmium tetroxide, chiral nitrogen ligands and superstoichiometricamounts of potassium hexacyanoferrate and potassium carbonate asoxidant. Review articles describing this methodology may be found, forexample, in “Asymmetric Dihydroxylation Reactions” M. Beller, K. B.Sharpless, in B. Cornils, W. A. Herrmann (Eds.) VCH, 1996, Weinheim, andH. C. Kolb, M. S. Van Nieuwenhze, K. B. Sharpless, Chem. Rev. 1994, 94,2483.

A critical disadvantage of the Sharpless dihydroxylation is the use of anumber of equivalents of potassium hexacyanoferrate as oxidant (Y.Ogino, H. Chen, H. L. Kwong, K. B. Sharpless, Tetrahedron Lett. 1991,32, 3965). Apart from the cost of the oxidant, the formation of largeamounts of salt and metal wastes is, in particular, ecologicallydisadvantageous. Thus, both the price and the superstoichiometric amountof the iron complex to be used (3 mol=990 g per 1 mol of substrate) withaddition of potassium carbonate (3 mol=420 g) is a considerabledisadvantage in a synthesis of the diols on a relatively industrialscale. Processes for the electrochemical oxidation of the Na₄[Fe(CN)₆]formed in the reaction to Na₃[Fe(CN)₆] (Sepracor Inc. (Y. Gao, C. M.Zepp), PCT Int. Appl. WO 9.317.150, 1994; Anon., Chem. Eng. News, 1994,72 (24), 41) are also difficult to implement on an industrial scalesince electrochemical processes are generally too expensive due to theapparatus required.

Although the literature discloses less expensive oxidants fordihydroxylations (for example chlorates; K. A. Hofmann, Chem. 1912, 45,3329; H₂O₂ in tert-butanol: N. A. Milas, J.-H. Trepagnier, J. T. Nolan,M. Ji. Iliopolus, J. Am. Chem. Soc. 1959, 81, 4730: tert-butylhydroperoxide in the presence of Et₄NOH; K. B. Sharpless, K. Akashi, J.Am. Chem. Soc. 1976, 98, 1986: P. H. J. Carisen, T. Katsuki, V. S.Martin, K. B. Sharpless, J. Org. Chem. 1981, 46, 3936; F. X. Webster, J.Rivas-Enterrios, R. M. Silverstein, J Org. Chem. 1987, 52, 689; V. S.Martin, M. T. Nunez, C. E. Tonn, Tetrahedron Lett. 1988, 29, 2701; M.Caron, P. R. Carlier, K. B. Sharpless, J Org. Chem. 1988, 53, 5185,tertiary amine oxides and, in most cases, N-methylmorpholine N-oxide; W.P. Schneider, A. V. Mcintosh, U.S. Pat. No. 2.769.824 (1956); V. VanRheenen, R. C. Kelly, D. Y. Cha, Tetrahedron Lett. 1976, 17, 1973), noneof the processes mentioned allow preparation of chiral diols with goodenantioselectivities.

To avoid the indicated disadvantages of the known catalytic processusing potassium hexacyanoferrate, it is an object of the invention todevelop a novel process for asymmetric dihydroxylation which giveschiral 1,2-diols in high yield, enantioselectivity and purity using aninexpensive reoxidant and which is suitable for industrialimplementation.

This object is achieved by a process for the asymmetric dihydroxylationof olefins by means of osmium catalysts, in which, according to theinvention, monofunctional, bifunctional and/or polyfunctional 1,2-diolsof the formula (I)

R¹R²C(OH)—C(OH)R³R⁴  (I)

where

R¹ to R⁴ are each, independently of one another, hydrogen, alkyl, CN,COOH, COO-alkyl, COO-aryl, CO-alkyl, CO-aryl, O-alkyl, O-aryl,O-CO-aryl, O-CO-alkyl, OCOO-alkyl, N-alkyl₂, NH-alkyl, N-aryl₂, NH-aryl,NO, NO₂, NOH, aryl, fluorine, chlorine, bromine, iodine, NO₂, Si-alkyl₃,CHO, SO₃H, SO₃-alkyl, SO₂-alkyl, SO-alkyl, CF₃, NHCO-alkyl, CONH₂,CONH-alkyl, NHCOH, NHCOO-alkyl, CHCHCO₂-alkyl, CHCHCO₂H, PO-(aryl)₂,PO-(alkyl)₂, PO₃H₂, PO(O-alkyl)₂, where alkyl represents an aliphaticorganic group having from 1 to 18 carbon atoms which may be linear,branched and/or cyclic and aryl is a five-, six- or seven-memberedaromatic ring which contains from 4 to 14 carbon atoms and may be fusedand contain from 0 to 3 hetero atoms such as N, O, S and where the alkyland/or the aryl group may bear up to six further substituents selectedindependently from among hydrogen, alkyl, O-alkyl, OCO-alkyl, O-aryl,aryl, fluorine, chlorine, bromine, iodine, OH, NO₂, NO, Si-alkyl₃, CN,COOH, CHO, SO₃H, NH₂, NH-alkyl, N-alkyl₂, PO-alkyl₂, SO₂-alkyl,SO-alkyl, CF₃, NHCO-alkyl, COO-alkyl, CONH₂, CO-alkyl, NHCOH,NHCOO-alkyl, CO-aryl, COO-aryl, PO-aryl₂, PO₃H₂, PO(O-alkyl)₂,SO₃-alkyl, where alkyl and aryl are as defined above,

are obtained by reacting olefins of the formula (II)

R¹R²C═CR³R⁴  (II)

where

R¹ to R⁴ are as defined above,

with molecular oxygen in the presence of a catalytic amount of an osmiumcompound and a chiral amine in water or a water-containing solventmixture at a pH of from 7.5 to 13.

In particular, compounds of the formula (I) are prepared using olefinsof the formula (II) in which the substituents R¹ to R⁴ are each,independently of one another, hydrogen, alkyl, CN, COOH, COO-alkyl,COO-aryl, CO-alkyl, CO-aryl, O-alkyl, O-aryl, N-alkyl₂, aryl, fluorine,chlorine, bromine, iodine, CHO, CF₃, NHCO-alkyl, CONH₂, CONH-alkyl,NHCOO-alkyl. Here, alkyl and aryl are as defined above.

Particular preference is given to a process in which diols of theformula (I) in which R¹ to R⁴ are each, independently of one another,hydrogen, alkyl, CN, COOH, COO-alkyl, CO-alkyl, CO-aryl, O-alkyl,O-aryl, aryl, fluorine, chlorine, bromine, CHO, NHCO-alkyl. Here alkyland aryl are as defined above.

The process of the invention is carried out in the presence of water. Ithas been found to be advantageous to use a further organic solvent inaddition to the olefin. The process of the invention can also, in thecase of various olefins, be carried out in the olefin/water mixturewithout further solvent. Further solvents used are generally inertorganic solvents. Suitable solvents are aliphatic ethers, aromatic oraliphatic hydrocarbons, alcohols and esters, halogenated hydrocarbons,dipolar aprotic solvents such as dialkyl sulfoxides, N,N-dialkylamidesof aliphatic carboxylic acids and also mixtures thereof. Preference isgiven to alcohols, esters and ethers. The aqueous phase used isgenerally a basic aqueous solution having a pH of from 7.5 to 13. Thebasic pH of the solution is achieved by addition of a base to the water.In general, it is advantageous to carry out the process in bufferedaqueous solutions, preferably at a pH of from 8 to 13. The bufferedsolution is prepared by addition of known buffers to water.

To enable the diol products to be separated off readily, it is sometimesadvantageous to use an aqueous salt solution or buffered aqueous saltsolution, for example an aqueous solution of an alkali metal halide oralkaline earth metal halide, as solvent in place of water or bufferedaqueous solutions.

The oxidant used in the process of the invention is molecular oxygen ora gas mixture comprising molecular oxygen. Preference is given to gasmixtures comprising at least 15% by volume of oxygen. Particularpreference is given to air and oxygen gas having an oxygen content of>95%.

The reaction preferably proceeds at temperatures of from 20 to 150° C.In many cases, it has been found to be useful to employ temperatures offrom 30 to 120° C., preferably from 40 to 80° C. The process of theinvention can be carried out at atmospheric pressure, e.g. by passingoxygen through the reaction solution. However, a faster reaction ratecan be achieved when a superatmospheric pressure of oxygen is employed.The process can be carried out at pressures of up to 200 bar, but isusually carried out at a pressure of not more than 60 bar and preferablyin the range from atmospheric pressure to 20 bar.

Chiral ligands used are chiral amines known from the literature (H. C.Kolb, M. S. Van Nieuwenhze', and K. B. Sharpless, Chem Rev. 1994, 94,2483-2547), for example diaminocyclohexane derivatives, substituteddiaminoethanes, bispiperazine, bispyrrolidine, bistetrahydropyridinecompounds, 1,4-diazabicyclo[2.2.2]octane derivatives, substitutedisooxazolidines, in particular (DHQD)₂PHAL (hydroquinidine1,4-phthalazinediyl diether) and (DHQ)₂PHAL (hydroquinine1,4-phthalazinediyl diether) and (DHQ)₂Pyr (hydroquinine2,5-diphenyl-4,6-pyrimidinyl diether).

The osmium catalysts used are generally osmium compounds in theoxidation states +8 and +6. However, it is also possible to use osmiumcatalyst precursors in low oxidation states. These are converted underthe reaction conditions into the catalytically active Os(VIII) andOs(VI) species. As osmium catalysts or catalyst precursors, it ispossible to use, for example, OsO₄, K₂Os₂(OH)₄, Na₂Os₂(OH)₄, Os₃(CO)₁₂,OsCl₃, H₂OsCl₆, [CF₃SO₃Os(NH₃)₅](O₃SCF₃)₂, OsO₄ on vinylpyridine,Bu^(t)NOsO₃.

In the process of the invention, the osmium catalyst is used incatalytic amounts relative to the olefin. In general, use is made offrom 0.2 to 0.00001 equivalents, based on olefin, preferably from 0.1 to0.0001 equivalents and particularly preferably from 0.08 to 0.0005equivalents.

The ratio of amine to osmium is from 0.01:1 to 1 000:1, preferably from0.1:1 to 100:1. Particular preference is given to using ratios of amineto osmium of from 1:50 to 50:1.

When using bulky olefins, in particular trisubstituted andtetrasubstituted olefins, it is sometimes advantageous to use acocatalyst to hydrolyze the osmate ester formed as an intermediate. Thiscocatalyst is an amide which promotes the hydrolysis, for example asulfonamide and/or carboxamide. Particular preference is given to theaddition of methylsulfonamide.

The cocatalyst is used in an amount of from 0.01 mol % to 10 mol %(based on olefin), preferably from 0.1 to 5 mol %.

The particular advantage of the process of the invention is the use ofoxygen or oxygen-containing gases as reoxidant. Despite thecomparatively difficult reoxidation process, high enantioselectivitiescan be achieved. The catalyst productivity can be increased by treatingthe aqueous catalyst phase which has been used once with olefin again.In this way, the catalyst costs for the process of the invention areminimized, so that even industrial processes can be carried outeconomically.

The process of the invention is particularly surprising and novel sinceno asymmetric osmium-catalyzed dihydroxylation reactions to form1,2-diols using oxygen as reoxidant were known in the past. The novelcombination described in the process of the invention of addition of aligand which accelerates the dihydroxylation and carrying out theprocess in a strongly basic buffered solution surprisingly leads to anenantioselective dihydroxylation process even in the presence of oxygen.The process of the invention demonstrates for the first time that thestatements made in the known literature in respect of osmium-catalyzeddihydroxylation using oxygen are wrong.

The particular advantages of the novel process are the price advantageof the oxidant, the simplicity of the procedure and the high selectivityof the process compared to known processes using potassiumhexacyanoferrate.

The chiral 1,2-diols prepared according to the invention can be used,inter alia, as precursors for agrochemicals, cosmetics, pharmaceuticalsand chiral polymers.

The following examples illustrate the process of the invention withoutrestricting it to the examples presented.

EXAMPLES Example 1

18.4 mg of K₂OsO₄×2H₂O (0.05 mmol) are weighed into a Schlenk vessel.While stirring by means of a magnetic stirrer, 25 ml of 0.4-0.5 molarNa₃PO₄/Na₂HPO₄ buffer solution having a pH of 11.2 and 10 ml of2-methyl-2-propanol are added thereto, resulting in formation of 2phases. The vessel is heated to 50° C. on a water bath and flushed withoxygen. After addition of 173 μl of styrene (1.5 mmol), the reactionvessel is connected to a burette filled with oxygen and the reactionsolution is stirred at 50° C. under a slightly superatmospheric O₂pressure (about 50 cm of water) for 24 hours.

The reaction mixture is worked up as described below:

2 g of sodium bisulfite and 10 ml of ethyl acetate are added to thereaction solution. After stirring for 10 minutes, the upper organicphase is separated off and the aqueous phase is shaken with 10 ml ofethyl acetate. The organic phases are combined, dried over anhydroussodium sulfate and evaporated to dryness on a rotary evaporator.

This gives 130 mg of(R)/(S)-1-phenyl-1,2-ethanediol, 63%.

To isolate any acidic product formed, the aqueous solution is acidifiedand shaken twice with 15 ml each time of ether. This gives 20 mg of acrystalline product of which more than 90% is made up by benzoic acid.

Example 2

The procedure of example 1 is repeated with 7.8 mg (0.01 mmol) of(DHQD)₂PHAL (hydroquinidine 1,4-phthalazinediyl diether) being added tothe osmium salt. This gives 155 mg of (R)-(+)-1-phenyl-1,2-ethanediol(75%), ee 65% (HPLC), and 30 mg of benzoic acid.

Example 3

18.4 mg of K₂OsO₄×2H₂O (0.05 mmol) and 7.8 mg (0.01 mmol) of (DHQD)₂PHALare weighed into a Schlenk vessel. While stirring by means of a magneticstirrer, 25 ml of a 0.3 molar borax/NaOH buffer solution having a pH of10.2,4 g of NaCl and 10 ml of 2-methyl-2-propanol are added, resultingin formation of 2 phases. The vessel is heated to 50° C. on a water bathand flushed with oxygen. After addition of 288 μof styrene (2.5 mmol),the reaction vessel is connected to a burette filled with oxygen, andthe reaction solution is stirred at 50° C. under a slightlysuperatmospheric O₂ pressure (about 50 cm of water) for 24 hours. Thereaction mixture is worked up as described in example 1.

This gives 200 mg of (R)-(+)-1-phenyl-1,2-ethanediol (58%), ee 82%(HPLC), and 40 mg of benzoic acid.

Example 4

1.5 mmol of styrene are reacted with 18.4 mg of K₂OsO₄×2H₂O (0.05 mmol)and 7.8 mg (0.01 mmol) of (DHQD)₂PHAL as described in example 1, but thereaction temperature was 30° C. and the reaction time was 62 hours.

After work-up, this gives 107 mg of predominantly(R)-(+)-1-phenyl-1,2-ethanediol (52%), ee 71% (HPLC), and 40 mg ofbenzoic acid.

Example 5

18.4 mg of K₂OsO₄×2H₂O (0.05 mmol) are reacted with 1.5 mmol of styreneas described in example 1. Prior to the addition of styrene, 8.8 mg(0.01 mmol) of (DHQ)₂Pyr (hydroquinine 2,5-diphenyl-4,6-pyrimidinyldiether) are added. This gives 141 mg of predominantly(S)-(−)-1-phenyl-1,2-ethanediol (68%), ee 23% (HPLC), and 40 mg ofbenzoic acid.

Example 6

Using the procedure of example 1, 231 mg of 2-vinylnaphthalene (1.5mmol) as substrate are reacted with 18.4 mg of K₂OsO₄×2H₂O (0.05 mmol)with addition of 7.8 mg (0.01 mmol) of (DHQ)₂PHAL (hydroquinine1,4-phthalazinediyl diether). As a difference from example 1, thereaction time was 7 hours. After work-up, this gives 227 mg of(S)-1-(2-naphthyl)-1,2-ethanediol (80%), ee 82% (HPLC). 34 mg of acrystalline product consisting predominantly of 2-naphthalenecarboxylicacid are obtained from the ether solution.

Example 7

Using a method analogous to example 1, 18.4 mg of K₂OsO₄×2H₂O (0.05mmol) are reacted with 195 μl (1.5 mmol) of α-methylstyrene withaddition of 7.8 mg (0.01 mmol) of (DHQ)₂PHAL in the 2-phase systemindicated.

After work-up in the manner described, this gives 180 mg ofpredominantly (S)-2-phenyl- 1,2-propanediol (79%), ee 60% (GC).

Example 8

Using a method analogous to example 1, 18.4 mg of K₂OsO₄×2H₂O (0.05mmol) are reacted with 130 μl (1 mmol) of trans-β-methylstyrene withaddition of 7.8 mg (0.01 mmol) of (DHQD)₂PHAL.

After the usual work-up, this gives 126 mg of(R,R)-1-phenyl-1,2-propanediol (80%).

Example 9

7.4 mg of K₂OsO₄×2H₂O (0.02 mmol) are weighed into a Schlenk vessel.While stirring by means of a magnetic stirrer, 25 ml of a buffersolution having a pH of 10.4 and prepared from 0.5 molar K₂HPO₄ solutionand 2 molar NaOH, together with 10 ml of 2-methyl-2-propanol are added,resulting in formation of 2 phases. The vessel is heated to 50° C. on awater bath and flushed with oxygen. After addition of 230 μl of styrene(2 mmol), the reaction vessel is connected to a burette filled withoxygen and the reaction solution is stirred at 50° C. under a slightlysuperatmospheric O₂ pressure (about 50 cm of water) for 24 hours.

The reaction mixture is worked up as described below.

2 g of sodium bisulfite and 20 ml of ethyl acetate are added to thereaction solution. After stirring for 10 minutes, the upper organicphase is separated off. Dialcohol and unreacted olefin are determined bymeans of GC.

Yield of 1-phenyl-1,2-ethanediol: 43% (selectivity: 57%).

Example 10

The procedure of example 9 is repeated, but 0.02 mmol of (DHQD)₂PHAL isadded to the osmium salt.

Yield of (R)-1-phenyl-1,2-ethanediol: 49% (selectivity: 74%), ee 89%(HPLC).

Example 11

The procedure of example 9 is repeated, but 0.06 mmol of (DHQD)₂PHAL isadded. 308 mg of 2-vinylnaphthalene (2 mmol) are used as substrate;dialcohol and unreacted olefin are in this case determined by means ofHPLC.

Yield of (R)-1-(2-naphthyl)-1,2-ethanediol: 55% (selectivity: 76%), ee93% (HPLC).

Example 12

As described in example 9, but a buffer solution of pH=11.2 is used and7.4 mg of K₂OsO₄×2H₂O (0.02 mmol)/0.06 mmol of (DHQD)₂PHAL are reactedwith 318 μl of 1-phenyl-1-cyclohexene (2 mmol).

Yield of (1R,2R)-1-phenyl-1,2-cyclohexanediol: 80% (selectivity: 83%),ee 90% (HPLC).

Example 13

As described in example 9, but 3.7 mg of K₂OsO₄×2H₂O (0.01 mmol)/0.03mmol of (DHQD)₂PHAL are reacted with 260 μl of α-methylstyrene (2 mmol)over a reaction time of 19 hours.

Yield of (R)-2-phenyl-1,2-propanediol: 96% (selectivity: 96%), ee 81%(GC).

Example 14

The procedure of example 13 is repeated using (DHQD)₂PYR (hydroquinidine2,5-diphenyl-4,6-pyrimidinediyl diether) as ligand.

Yield of (R)-2-phenyl-1,2-propanediol: 95% (selectivity: 95%), ee 43%(GC).

Example 15

The procedure of example 13 is repeated using (DHQD)₂AQN (hydroquinidineanthraquinone-1,4-diyl diether) as ligand.

Yield of (R)-2-phenyl-1,2-propanediol: 96% (selectivity: 96%), ee 65%(GC).

Example 16

The procedure of example 13 is repeated using 0.006 mmol of (DHQD)₂PHEN(hydroquinidine 9-phenanthryl ether) as ligand.

Yield of (R)-2-phenyl-1,2-propanediol: 94% (selectivity: 96%), ee 42%(GC).

Example 17

Using a method analogous to example 13, 1-octene is reacted over areaction time of 15 hours.

Yield of (R)-1,2-octanediol: 98% (selectivity: 99%), ee 65% (HPLC,bisbenzoate).

Example 18

As described in example 9, but 7.4 mg of K₂OsO₄×2H₂O (0.02 mmol)/0.06mmol of (DHQD)₂PHAL are reacted with 240 μl of 1-methyl-1-cyclohexene (2mmol) over a reaction time of 12 hours using a buffer solution having apH of 11.2.

Yield of (1R,2R)-1-methyl-1,2-cyclohexanediol: 82% (selectivity: 85%),ee 49% (HPLC, bisbenzoate).

Example 19

Method analogous to example 9, but 320 μl of allyltrimethylsilane (2mmol) are reacted over a reaction time of 6 hours.

Yield of (S)-3-trimethylsilyl- 1,2-propanediol: 79% (selectivity: 89%),ee 15% (HPLC, bisbenzoate).

Example 20

As described in example 9, but 14.7 mg of K₂OsO₄×2H₂O (0.04 mmol)/0.12mmol of (DHQD)₂PHAL are reacted with 380 μl of trans-5-decene (2 mmol)over a reaction time of 18 hours using a buffer solution having a pH of12.0.

Yield of (R,R)-5,6-decanediol: 95% (selectivity: 98%), ee 88% (HPLC,bisbenzoate).

Example 21

Using a method analogous to example 20, 245 μl of 2-methyl-2-pentene (2mmol) are reacted at pH=11.2.

Yield of (2R,3R)-2-methyl-2,3-pentanediol: 88% (selectivity: 87%), ee87% (HPLC, bisbenzoate).

Example 22

Using a method analogous to example 20, 240 μl of 2-vinyl-1,3-dioxolane(2 mmol) are reacted at pH=10.4.

Yield of (S)-2-(1,2-dihydroxyethyl)-1,3-dioxolane: 63% (selectivity:86%), ee 23% (HPLC, bisbenzoate).

Example 23

Using a method analogous to example 22, 692 mg of1H,1H,2H-perfluoro-1-octene (2 mmol) are reacted using (DHQD)₂AQN asligand.

Yield of 1H,1H,2H-perfluorooctane-1,2-diol: 40% (selectivity: 83%), ee45% (HPLC, bisbenzoate).

Example 24

7.4 mg of K₂OsO₄×2H₂O (0.02 mmol)/0.06 mmol of (DHQD)₂PHAL are reactedwith 275 ml of allyl phenyl ether (2 mmol) over a reaction time of 18hours as described in example 9.

Yield of(S)-3-phenoxy-1,2-propanediol: 80% (selectivity: 95%), ee 74%(HPLC).

Example 25

Using a method analogous to example 24, 295 μl of allyl phenyl sulfide(2 mmol) are reacted using (DHQD)₂AQN as ligand.

Yield of (S)-(2,3-dihydroxypropyl) phenyl sulfide: 67% (selectivity:92%), ee 63% (HPLC).

Example 26

0.002 mmol of K₂OsO₄×2H₂O dissolved in water, 0.030 mmol of (DHQD)₂PHALand 25 ml of buffer solution having a pH of 10.4 and prepared from 0.5molar K₂HPO₄ solution and 2 molar NaOH, together with 12 ml of2-methyl-2-propanol are placed in a glass vessel located in a pressureautoclave, and the mixture is stirred by means of a magnetic stirrer. 2phases are formed. After addition of 260 μl of α-methylstyrene (2 mmol),the autoclave is pressurized with 3 bar of oxygen and is heated to50-55° C.

After 24 hours, the reaction mixture is worked up as described inexample 9.

Yield of (R)-2-phenyl-1,2-propanediol: 93% (selectivity: 93%), ee 78%(GC).

Example 27

0.001 mmol of K₂OsO₄×2H₂O/0.015 mmol of (DHQD)₂PHAL are reacted with 260μl of a-methylstyrene (2 mmol) at an O₂ pressure of 5 bar as describedin example 26.

Yield of (R)-2-phenyl- 1,2-propanediol: 94% (selectivity: 94%), ee 77%(GC).

Example 28

The procedure of example 26 is repeated, but the autoclave ispressurized with 8 bar of compressed air in place of pure oxygen.

Yield of (R)-2-phenyl-1,2-propanediol: 80% (selectivity: 93%), ee 80%(GC).

What is claimed is:
 1. A process for the asymmetric dihydroxylation ofolefins using osmium catalysts to prepare monofunctional, bifunctionaland/or polyfunctional chiral 1,2-diols of the formula (I)R¹R²C(OH)—C(OH)R³R⁴  (I) where R¹ to R⁴ are each, independently of oneanother, hydrogen, alkyl, CN, COOH, COO-alkyl, COO-aryl, CO-alkyl,CO-aryl, O-alkyl, O-aryl, O—CO-aryl, O—CO-alkyl, OCOO-alkyl, N-alkyl₂,NH-alkyl, N-aryl₂, NH-aryl, NO, NO₂, NOH, aryl, fluorine, chlorine,bromine, iodine, Si-alkyl₃, CHO, SO₃H, SO₃-alkyl, SO₂-alkyl, SO-alkyl,CF₃, NHCO-alkyl, CONH₂, CONH-alkyl, NHCOH, NHCOO-alkyl, CHCHCO₂-alkyl,CHCHCO₂H, PO-(aryl)₂, PO(alkyl)₂, PO₃H₂, or PO(O-alkyl)₂, where alkyl isa linear, branched, and/or cyclic aliphatic organic group having from 1to 18 carbon atoms and aryl is a five-, six-, or seven-membered aromaticring containing from 4 to 14 carbon atoms and from 0 to 3 heteroatomsand is optionally fused, and where the alkyl and/or the aryl groupoptionally bears up to six substituents selected independently from thegroup consisting of hydrogen, alkyl, O-alkyl, OCO-alkyl, O-aryl, aryl,fluorine, chlorine, bromine, iodine, OH, NO₂, NO, Si-alkyl₃, CN, COOH,CHO, SO₃H, NH₂, NH-alkyl, N-alkyl₂, PO-alkyl₂, SO₂-alkyl, SO-alkyl, CF₃,NHCO-alkyl, COO-alkyl, CONH₂, CO-alkyl, NHCOH, NHCOO-alkyl, CO-aryl,COO-aryl, PO-aryl₂, PO₃H₂, PO(O-alkyl)₂, and SO₃-alkyl, where alkyl andaryl are as defined above, comprising reacting an olefin of the formula(II)  R¹R²C═CR³R⁴  (II) where R¹ to R⁴ are defined as for formula (I),with molecular oxygen in the presence of an osmium compound and a chiralamine ligand in water or a water-containing solvent mixture at a pH offrom 8.5 to
 13. 2. The process according to claim 1 for preparingcompounds of the formula (I) wherein for olefins of the formula (II) thesubstituents R¹ to R⁴ are each, independently of one another, hydrogen,alkyl, CN, COOH, COO-alkyl, COO-aryl, CO-alkyl, CO-aryl, O-alkyl,O-aryl, N-alkyl₂, aryl, fluorine, chlorine, bromine, iodine, CHO, CF₃,NHCO-alkyl, CONH₂, CONH-alkyl, or NHCOO-alkyl.
 3. The process accordingto claim 1 wherein chiral diols of the formula (I) in which R¹ to R⁴ areeach, independently of one another, hydrogen, alkyl, CN, COOH,COO-alkyl, CO-alkyl, CO-aryl, O-alkyl, O-aryl, aryl, fluorine, chlorine,bromine, CHO, or NHCO-alkyl are prepared.
 4. The process according toclaim 1 wherein the reaction medium comprises an aqueous solution, theolefin, and an organic solvent.
 5. The process according to claim 1wherein the solvent comprises one or more organic solvents selected fromthe group consisting of aliphatic ethers, aromatic and aliphatichydrocarbons, alcohols, and esters, halogenated hydrocarbons, dipolaraprotic solvents, and mixtures thereof.
 6. The process according toclaim 5 wherein the dipolar aprotic solvent is a dialkyl sulfoxide or aN,N-dialkylamide of an aliphatic carboxylic acid.
 7. The processaccording to claim 1 wherein the oxidant is oxygen or a gas mixturecomprising at least 15% by volume of oxygen.
 8. The process according toclaim 1 wherein the reaction proceeds at a temperature of from 20 to150° C. and a pressure of up to 200 bar.
 9. The process according toclaim 1 wherein the chiral amine is a chiral diaminocyclohexanederivative, substituted diaminoethane, bispiperazine, bispyrrolidone, orbistetrahydropyridine compound, 1,4-diazabicyclo[2.2.2]octanederivative, or substituted isooxazolidine.
 10. The process according toclaim 1 wherein the chiral amine is chiral hydroquinidine1,4-phthalazinediyl diether, hydroquinine 1,4-phthalazinediyl diether,or hydroquinine 2,5-diphenyl-4,6-pyrimidinyl diether.
 11. The processaccording to claim 1 wherein a sulfonamide is added as a cocatalyst. 12.The process according to claim 11 wherein the sulfonamide cocatalyst isa methylsulfonamide and/or a carboxamide.
 13. The process according toclaim 1 wherein one or more of the osmium compounds OsO₄, K₂Os₂(OH)₄,Na₂Os₂(OH)₄, Os₃(CO)₁₂, OsCl₃, H₂OsC₆, [CF₃SO₃Os(NH₃)₅](O₃SCF₃)₂, OsO₄on vinylpyridine, or Bu^(t)NOsO₃ are used as catalysts and/or catalystprecursors.
 14. The process according to claim 1 wherein the osmiumcatalyst is used in amounts of from 0.2 to 0.00001 equivalents, based onthe olefin.
 15. The process according to claim 1 wherein the ratio ofamine to osmium is from 0.01:1 to 1 000:1.